In well pumping apparatus, it is customary to employ a stuffing box at the wellhead to prevent oil, water and gases produced under pressure by the pumping apparatus from escaping into the atmosphere.
Generally, the stuffing box is disposed in surrounding relation to the polished rod in order to guide or center the polished rod for vertical reciprocal movement without the escape of produced liquids or gases. Typically, the stuffing box is able to prevent the loss of produced liquids or gases by utilization of a series of packing coils which are compressed within the stuffing box by bearings at opposite ends of the coils and are squeezed or otherwise forced against the coils by threaded end members. The stuffing box is connected directly into the well production string, for example, by threading the lower end of a pack off assembly into a conventional flow tee or pipe fitting.
It is important that the polished rod be centralized in the stuffing box. If the polished rod is not centralized, excessive packing wear and leakage can result. For instance, excessive packing wear will allow the escape of produced fluids and gases into the environment.
It is well known that leakage of fluids and gases is often encountered in oil well stuffing boxes due to packing wear. This condition may be alleviated by providing a better means of centralizing the polished rod in the stuffing box. By accurately centralizing the polished rod in the stuffing box, the stress of centralizing the polished rod will be taken from the stuffing box packing material. By taking the centralizing stress off the packing material, packing material wear will be reduced. By reducing stuffing box packing material wear, leaking or emissions of produced fluids and gases may be reduced.
It has been found that greater efficiencies can be realized both in down time and in preventing the escape of fluids and gases into the atmosphere from a pumping well through the utilization of a novel and improved rod guide assembly which will accurately center and guide the polished rod for reciprocation. Utilization of a rod guide assembly or other bearing assembly is further enhanced by incorporating one or more scraper rings into one of the guide members to minimize scale build-up as well as the amount of pressure that must be exerted on the packing material in the assembly.